Dendritic cell vaccines for melanoma: past, present and future

A review of the progress and challenges of developing dendritic-based vaccines against hepatitis B virus (HBV)

Hepatitis B virus (HBV) infections that last a long time are a significant public health problem worldwide. About 254 million people around the world are chronically sick with HBV. Each year, 1.2 million new cases occur, and in 2022, 1.1 million people will die from the disease. So, it has been essential to work on finding ways to treat and avoid HBV. The process of therapeutic vaccination involves giving people a non-infectious form of a virus to start or improve immune reactions specific to HBV. This helps keep HBV infections under control. Dendritic cells (DCs) play a significant part in beginning the adaptive immune response, which could decide how well an HBV infection is treated. DC-based treatment has been looked into for people with chronic HBV (CHB) infection and has shown some sound effects. Vaccines for CHB that use DCs boost antiviral immunity by improving T cells and breaking the immune system's resistance against HBV. In these vaccines, DCs are loaded with HBV antigens (like HBsAg, HBcAg, or peptides) outside of the body and then put back into the patient to make the immune system work better. In conclusion, this DC treatment is a biological therapy method with a good chance of being used. This study examined the different DC-based medicines that can treat and prevent HBV. Finally, we've talked about clinical studies, the current problems, how to fix them, and the future of this vaccine for treating and preventing HBV.

Combined Osteopontin Blockade and Type 2 Classical Dendritic Cell Vaccination as Effective Synergetic Therapy for Conjunctival Melanoma

Angiogenesis and immune protection are essential at the onset of tumorigenesis. Angiogenesis serves to nourish the tumor, and prevention of immune defenses, for example, by dendritic cells (DCs), allows tumor growth. In this study, we investigated whether there are factors with dual functions that are both angiogenic and immunomodulatory and represent a therapeutic target. We analyzed 1) innate immune responses intratumorally and in draining lymph nodes and 2) angiogenic factors in conjunctival melanoma (CM), a potentially lethal malignant tumor at the ocular surface whose immune and vascular responses are largely unknown. For this purpose, an HGF-Cdk4R24C model in immunocompetent C57BL/6 mice was used and revealed that CD103- type 2 classical DC (cDC2s) were the most abundant DC subtype in healthy conjunctiva, whereas in CM, CD103- cDC2s, CD103+ type 1 cDCs, monocyte-derived DCs, and plasmacytoid DCs were significantly increased. In our analysis of angiogenic factors in CM, the examination of 53 angiogenesis-related factors that might interact with DCs identified osteopontin (OPN) as a major tumor-derived protein that interacts with DCs. Consistent with these findings, 3) a dual therapeutic strategy that inhibited tumor cell function by an OPN blocking Ab while enhancing the immune response by cDC2 vaccination resulted in 35% failure of tumor development. Moreover, tumor progression, monocyte-derived DC infiltration, and intratumoral angiogenesis were significantly reduced, whereas survival and CD8+ T cell infiltration were increased in treated mice compared with the control group. Therefore, we identified OPN blockade in combination with cDC2 vaccination as a potential future therapeutic intervention for early stages of CM by combining antiangiogenic and host immune stimulating effects.

Nanobody-mediated SPECT/CT imaging reveals the spatiotemporal expression of programmed death-ligand 1 in response to a CD8+ T cell and iNKT cell activating mRNA vaccine

Rationale: Although promising responses are obtained in patients treated with immune checkpoint inhibitors targeting programmed death ligand 1 (PD-L1) and its receptor programmed death-1 (PD-1), only a fraction of patients benefits from this immunotherapy. Cancer vaccination may be an effective approach to improve the response to immune checkpoint inhibitors anti-PD-L1/PD-1 therapy. However, there is a lack of research on the dynamics of PD-L1 expression in response to cancer vaccination. Methods: We performed non-invasive whole-body imaging to visualize PD-L1 expression at different timepoints after vaccination of melanoma-bearing mice. Mice bearing ovalbumin (OVA) expressing B16 tumors were i.v. injected with the Galsome mRNA vaccine: OVA encoding mRNA lipoplexes co-encapsulating a low or a high dose of the atypical adjuvant α-galactosylceramide (αGC) to activate invariant natural killer T (iNKT) cells. Serial non-invasive whole-body immune imaging was performed using a technetium-99m (99mTc)-labeled anti-PD-L1 nanobody, single-photon emission computerized tomography (SPECT) and X-ray computed tomography (CT) images were quantified. Additionally, cellular expression of PD-L1 was evaluated with flow cytometry. Results: SPECT/CT-imaging showed a rapid and systemic upregulation of PD-L1 after vaccination. PD-L1 expression could not be correlated to the αGC-dose, although we observed a dose-dependent iNKT cell activation. Dynamics of PD-L1 expression were organ-dependent and most pronounced in lungs and liver, organs to which the vaccine was distributed. PD-L1 expression in lungs increased immediately after vaccination and gradually decreased over time, whereas in liver, vaccination-induced PD-L1 upregulation was short-lived. Flow cytometric analysis of these organs further showed myeloid cells as well as non-immune cells with elevated PD-L1 expression in response to vaccination. SPECT/CT imaging of the tumor demonstrated that the expression of PD-L1 remained stable over time and was overall not affected by vaccination although flow cytometric analysis at the cellular level demonstrated changes in PD-L1 expression in various immune cell populations following vaccination. Conclusion: Repeated non-invasive whole-body imaging using 99mTc-labeled anti-PD-L1 nanobodies allows to document the dynamic nature of PD-L1 expression upon vaccination. Galsome vaccination rapidly induced systemic upregulation of PD-L1 expression with the most pronounced upregulation in lungs and liver while flow cytometry analysis showed upregulation of PD-L1 in the tumor microenvironment. This study shows that imaging using nanobodies may be useful for monitoring vaccine-mediated PD-L1 modulation in patients and could provide a rationale for combination therapy. To the best of our knowledge, this is the first report that visualizes PD-L1 expression upon cancer vaccination.

Autologous dendritic cells loaded with antigens from self-renewing autologous tumor cells as patient-specific therapeutic cancer vaccines

A promising personal immunotherapy is autologous dendritic cells (DC) loaded ex vivo with autologous tumor antigens (ATA) derived from self-renewing autologous cancer cells. DC-ATA are suspended in granulocyte-macrophage colony stimulating factor at the time of each subcutaneous injection. Previously, irradiated autologous tumor cell vaccines have produced encouraging results in 150 cancer patients, but the DC-ATA vaccine demonstrated superiority in single-arm and randomized trials in metastatic melanoma. DC-ATA have been injected into more than 200 patients with melanoma, glioblastoma, and ovarian, hepatocellular, and renal cell cancers. Key observations include: [1] greater than 95% success rates for tumor cell cultures and monocyte collection for dendritic cell production; [2] injections are well-tolerated; [3] the immune response is rapid and includes primarily TH1/TH17 cellular responses; [4] efficacy has been suggested by delayed but durable complete tumor regressions in patients with measurable disease, by progression-free survival in glioblastoma, and by overall survival in melanoma.

Treatment of melanoma with dendritic cell vaccines and immune checkpoint inhibitors: A mathematical modeling study

Dendritic cell (DC) vaccines and immune checkpoint inhibitors (ICIs) play critical roles in shaping the immune responses of tumor cells (TCs) and are widely used in cancer immunotherapies. Quantitatively evaluating the effectiveness of these therapies are essential for the optimization of treatment strategies. Here, based on the combined therapy of melanoma with DC vaccines and ICIs, we formulated a mathematical model to investigate the dynamic interactions between TCs and the immune system and understand the underlying mechanisms of immunotherapy. First, we obtained a threshold parameter for the growth of TCs, which is given by the ratio of spontaneous proliferation to immune inhibition. Next, we proved the existence and locally asymptotic stability of steady states of tumor-free, tumor-dominant, and tumor-immune coexistent equilibrium, and identified the existence of Hopf bifurcation of the proposed model. Furthermore, global sensitivity analysis showed that the growth of TCs strongly correlates with the injection rate of DC vaccines, the activation rate of CTLs, and the killing rate of TCs. Finally, we tested the efficacy of multiple monotherapies and combined therapies with model simulations. Our results indicate that DC vaccines can decelerate the growth of TCs, and ICIs can inhibit the growth of TCs. Besides, both therapies can prolong the lifetime of patients, and the combined therapy of DC vaccines and ICIs can effectively eradicate TCs.

Exosomal-long non-coding RNAs journey in colorectal cancer: Evil and goodness faces of key players

Exosomes are nano-vesicles (NVs) secreted by cells and take part in cell-cell communications. Lately, these exosomes were proved to have dual faces in cancer. Actually, they can contribute to carcinogenesis through epithelial-mesenchymal transition (EMT), angiogenesis, metastasis and tumor microenvironment (TME) of various cancers, including colorectal cancer (CRC). On the other hand, they can be potential targets for cancer treatment. CRC is one of the most frequent tumors worldwide, with incidence rates rising in the recent decades. In its early stage, CRC is asymptomatic with poor treatment outcomes. Therefore, finding a non-invasive, early diagnostic biomarker tool and/or suitable defender to combat CRC is mandatory. Exosomes provide enrichment and safe setting for their cargos non-coding RNAs (ncRNAs) and proteins, whose expression levels can be upregulated ordown-regulated in cancer. Hence, exosomes can be used as diagnostic and/or prognostic tools for cancer. Moreover, exosomes can provide a novel potential therapeutic modality for tumors via loading with specific chemotherapeutic agents, with the advantage of possible tumor targeting. In this review, we will try to collect and address recent studies concerned with exosomes and their cargos' implications for CRC diagnosis and/or hopefully, treatment.

New Therapeutic Approaches for Conjunctival Melanoma-What We Know So Far and Where Therapy Is Potentially Heading: Focus on Lymphatic Vessels and Dendritic Cells

Conjunctival melanoma (CM) accounts for 5% of all ocular melanomas and arises from malignantly transformed melanocytes in the conjunctival epithelium. Current therapies using surgical excision in combination with chemo- or cryotherapy still have high rates for recurrences and metastatic disease. Lately, novel signal transduction-targeted and immune checkpoint inhibitors like cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors, programmed cell death protein-1 (PD-1) receptor inhibitors, BRAF- or MEK-inhibitors for systemic treatment of melanoma have improved the outcome even for unresectable cutaneous melanoma, improving patient survival dramatically. The use of these therapies is now also recommended for CM; however, the immunological background of CM is barely known, underlining the need for research to better understand the immunological basics when treating CM patients with immunomodulatory therapies. Immune checkpoint inhibitors activate tumor defense by interrupting inhibitory interactions between tumor cells and T lymphocytes at the so-called checkpoints. The tumor cells exploit these inhibitory targets on T-cells that are usually used by dendritic cells (DCs). DCs are antigen-presenting cells at the forefront of immune response induction. They contribute to immune tolerance and immune defense but in the case of tumor development, immune tolerance is often prevalent. Enhancing the immune response via DCs, interfering with the lymphatic pathways during immune cell migration and tumor development and specifically targeting tumor cells is a major therapeutic opportunity for many tumor entities including CM. This review summarizes the current knowledge on the function of lymphatic vessels in tumor growth and immune cell transport and continues to compare DC subsets in CM with related melanomas, such as cutaneous melanoma and mucosal melanoma.

Dendritic cells focus CTL responses toward highly conserved and topologically important HIV-1 epitopes

Background

During early HIV-1 infection, immunodominant T cell responses to highly variable epitopes lead to the establishment of immune escape virus variants. Here we assessed a type 1-polarized monocyte-derived dendritic cell (MDC1)-based approach to selectively elicit cytotoxic T lymphocyte (CTL) responses against highly conserved and topologically important HIV-1 epitopes in HIV-1-infected individuals from the Thailand RV254/SEARCH 010 cohort who initiated antiretroviral therapy (ART) during early infection (Fiebig stages I-IV).

Methods

Autologous MDC1 were used as antigen presenting cells to induce in vitro CTL responses against HIV-1 Gag, Pol, Env, and Nef as determined by flow cytometry and ELISpot assay. Ultra-conserved or topologically important antigens were respectively identified using the Epigraph tool and a structure-based network analysis approach and compared to overlapping peptides spanning the Gag proteome.

Findings

MDC1 presenting either the overlapping Gag, Epigraph, or Network 14–21mer peptide pools consistently activated and expanded HIV-1-specific T cells to epitopes identified at the 9–13mer peptide level. Interestingly, some CTL responses occurred outside known or expected HLA associations, providing evidence of new HLA-associated CTL epitopes. Comparative analyses demonstrated more sequence conservation among Epigraph antigens but a higher magnitude of CTL responses to Network and Gag peptide groups. Importantly, CTL responses against topologically constrained Gag epitopes contained in both the Network and Gag peptide pools were selectively enhanced in the Network pool-initiated cultures.

Interpretation

Our study supports the use of MDC1 as a therapeutic strategy to induce and focus CTL responses toward putative fitness-constrained regions of HIV-1 to prevent immune escape and control HIV-1 infection.

Funding

A full list of the funding sources is detailed in the Acknowledgment section of the manuscript.

Progress of exosomes in the diagnosis and treatment of lung cancer

The incidence and mortality of lung cancer account for first place all over the world. Lung cancer lacks early diagnostic biomarkers; lung cancer patients are usually diagnosed in both middle and advanced stages and have poor treatment outcomes. It is more important to find the first diagnostic tools for lung cancer with high specificity and sensitivity. Besides, exosomes are usually nanometer-sized bi-layered lipid vesicles formed and produced by various types of cells. As one of the main modes of intercellular communication, they can deliver multiple functional biomolecules, such as DNA, microRNAs, messenger RNA (mRNA), long non-coding RNA, and proteins, and the events as mentioned above affects different physiological processes of recipient cells. It has been reported that exosomes are involved in different types of cancer, including lung cancer. Various studies proved that exosomes are involved in multiple cancer processes such as cell proliferation, metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, and the tumor microenvironment in lung cancer. Tumor-derived exosomes (TEX) contain a variety of stimulatory and inhibitory factors involved in regulating immune response, which can affect the tumor microenvironment (TME) and thus participate in the formation and progression of lung cancer. This review's primary purpose to review the latest research progress of exosomes in diagnosing and treating lung cancer.

An update on GM-CSF and its potential role in melanoma management

GM-CSF drives the differentiation of granulocytes and monocyte/macrophages from hematopoietic stem cell progenitors. It is required for differentiating monocytes into dendritic cells (DC). Although approved for recovery of granulocytes/monocytes in patients receiving chemotherapy, G-CSF is preferred. Enthusiasm for GM-CSF monotherapy as a melanoma treatment was dampened by two large randomized trials. Although GM-CSF has been injected into tumors for many years, the efficacy of this has not been tested. There is a strong rationale for GM-CSF as a vaccine adjuvant, but it appears of benefit only for strategies that directly involve DCs, such as intratumor talimogene laherparepvec and vaccines in which DCs are loaded with antigen ex vivo and injected admixed with GM-CSF.

Cytokine network analysis of immune responses before and after autologous dendritic cell and tumor cell vaccine immunotherapies in a randomized trial

Background

In a randomized phase II trial conducted in patients with metastatic melanoma, patient-specific autologous dendritic cell vaccines (DCV) were associated with longer survival than autologous tumor cell vaccines (TCV). Both vaccines presented antigens from cell-renewing autologous tumor cells. The current analysis was performed to better understand the immune responses induced by these vaccines, and their association with survival.

Methods

110 proteomic markers were measured at a week-0 baseline, 1 week before the first of 3 weekly vaccine injections, and at week-4, 1 week after the third injection. Data was presented as a deviation from normal controls. A two-component principal component (PC) statistical analysis and discriminant analysis were performed on this data set for all patients and for each treatment cohort.

Results

At baseline PC-1 contained 64.4% of the variance and included the majority of cytokines associated with Th1 and Th2 responses, which positively correlated with beta-2-microglobulin (B2M), programmed death protein-1 (PD-1) and transforming growth factor beta (TGFβ1). Results were similar at baseline for both treatment cohorts. After three injections, DCV-treated patients showed correlative grouping among Th1/Th17 cytokines on PC-1, with an inverse correlation with B2M, FAS, and IL-18, and correlations among immunoglobulins in PC-2. TCV-treated patients showed a positive correlation on PC-1 among most of the cytokines and tumor markers B2M and FAS receptor. There were also correlative changes of IL12p40 with both Th1 and Th2 cytokines and TGFβ1. Discriminant analysis provided additional evidence that DCV was associated with innate, Th1/Th17, and Th2 responses while TCV was only associated with innate and Th2 responses.

Conclusions

These analyses confirm that DCV induced a different immune response than that induced by TCV, and these immune responses were associated with improved survival.

Trial registration Clinical trials.gov NCT004936930 retrospectively registered 28 July 2009

Survival Comparison between Melanoma Patients Treated with Patient-Specific Dendritic Cell Vaccines and Other Immunotherapies Based on Extent of Disease at the Time of Treatment

Encouraging survival was observed in single arm and randomized phase 2 trials of patient-specific dendritic cell vaccines presenting autologous tumor antigens from autologous cancer cells that were derived from surgically resected metastases whose cells were self-renewing in vitro. Based on most advanced clinical stage and extent of tumor at the time of treatment, survival was best in patients classified as recurrent stage 3 without measurable disease. Next best was in stage 4 without measurable disease, and the worst survival was for measurable stage 4 disease. In this study, the survival of these patients was compared to the best contemporary controls that were gleaned from the clinical trial literature. The most comparable controls typically were from clinical trials testing other immunotherapy approaches. Even though contemporary controls typically had better prognostic features, median and/or long-term survival was consistently better in patients treated with this dendritic cell vaccine, except when compared to anti-programmed death molecule 1 (anti-PD-1). The clinical benefit of this patient-specific vaccine appears superior to a number of other immunotherapy approaches, but it is more complex to deliver than anti-PD-1 while equally effective. However, there is a strong rationale for combining such a product with anti-PD-1 in the treatment of patients with metastatic melanoma.

Immune therapy of melanoma: Overview of therapeutic vaccines

Melanoma is the most serious type of skin cancer which develops from the occurrence of genetic mutations in the melanocytes. Based on the features of melanoma tumors such as location, genetic profile and stage, there are several therapeutic strategies including surgery, chemotherapy, and radiotherapy. However, because of the appearance resistance mechanisms, the efficiency of these treatments strategies may be reduced. It has been demonstrated that therapeutic monoclonal antibodies can improve the efficiency of melanoma therapies. Recently, several mAbs, such as nivolumab, pembrolizumab, and ipilimumab, were approved for the immunotherapy of melanoma. The antibodies inhibit immune checkpoint receptors such as CTL4 and pd-1. Another therapeutic strategy for the treatment of melanoma is cancer vaccines, which improve clinical outcomes in patients. The combination therapy using antibodies and gene vaccine give us a new perspective in the treatment of melanoma patients. Herein, we present the recent progressions in the melanoma immunotherapy, especially dendritic cells mRNA vaccines by reviewing recent literature.

Patient-specific dendritic cell vaccines with autologous tumor antigens in 72 patients with metastatic melanoma

Aim:

Metastatic melanoma patients were treated with patient-specific vaccines consisting of autologous dendritic cells loaded with antigens from irradiated cells from short-term autologous tumor cell lines.

Patients & methods:

A total of 72 patients were enrolled in a single-arm Phase I/II (NCT00948480) trial or a randomized Phase II (NCT00436930).

Results:

Toxicity was minimal. Median overall survival (OS) was 49.4 months; 5-year OS 46%. A 5-year OS was 72% for 18 recurrent stage 3 without measurable disease when treated and 53% for 30 stage 4 without measurable disease when treated. A total of 24 patients with measurable stage 4 when treated (median of four prior therapies) had an 18.5 months median OS and 46% 2-year OS.

Conclusion:

This dendritic cell vaccine was associated with encouraging survival in all three clinical subsets. Clinicaltrial.gov NCT00436930 and NCT00948480.

An update on the relevance of vaccine research for the treatment of metastatic melanoma

Signal transduction inhibitors and anticheckpoint antibodies have significantly improved survival for metastatic melanoma patients, but most still die within 5 years. Vaccine approaches to induce immunity to well-characterized melanoma-associated antigens, or to antigens expressed on allogeneic tumor cell lines, have not resulted in approved agents. Despite the limitations associated with the immunosuppressive tumor microenvironment, there now is one intralesional autologous vaccine approved for patients who have primarily soft-tissue metastases. There is continued interest in patient-specific vaccines, especially dendritic cell vaccines that utilize ex vivo loading of autologous antigen, thus bypassing certain in vivo immunosuppressive cells and cytokines. Because of their mechanism of action and limited toxicity, they are potentially synergistic or additive to other antimelanoma therapies.

Is there a role for therapeutic cancer vaccines in the age of checkpoint inhibitors?

Because of the recent success of monoclonal antibody checkpoint inhibitors, and the disappointing results of most therapeutic cancer vaccine trials, it has been questioned whether there is any potential role for such products going forward. In my opinion the answer is “yes” based on the following: [1] there is a persistent unmet clinical need because the majority of patients do not benefit from anti-checkpoint therapy, [2] there is evidence that not all patients make immune responses to their tumors, [3] there is evidence that immune responses to autologous tumor antigens can be induced by patient-specific vaccines, [4] there is clinical evidence from the pre-checkpoint era that suggests survival can be positively impacted by such patient-specific vaccines, and [5] the 2 available therapeutic vaccines that have received regulatory approval are quite limited in terms of their therapeutic benefit.